Pad printing is an example of a conventional method for forming an image on a medium. In pad printing, the following procedure for forming an image is known: (1) a flat master plate (intaglio plate) on which a printing pattern is formed is prepared; (2) ink is pressed into the printing pattern of this flat master plate; (3) an elastic transfer pad is pressed against the flat master plate from above to transfer the ink in the printing pattern to the transfer pad; and (4) the transfer pad is pressed against the medium to transfer the ink from the transfer pad to the medium.
In another known method used in recent times, an image is formed on a medium in the following manner: (1) ink is applied to a flat master plate using an ink jet printer; (2) the ink on the flat master plate is thickened; (3) an elastic transfer pad is pressed against the flat master plate from above to transfer the ink in the printing pattern to the transfer pad; and (4) the transfer pad is pressed against the medium to transfer the ink from the transfer pad to the medium. (For example, see Patent Document 1.)